#define _CRT_SECURE_NO_WARNING
#include<iostream>
#include<vector>
#include<queue>
using namespace std;
class Solution {
public:
    int dx[4] = { 0,0,1,-1 };
    int dy[4] = { 1,-1,0,0 };
    int vir[301][301];
    int m, n;
    int numIslands(vector<vector<char>>& grid) {
        m = grid.size(), n = grid[0].size();
        int ret = 0;
        for (int i = 0; i < m; i++)
        {
            for (int j = 0; j < n; j++)
            {
                if (grid[i][j] == '1' && !vir[i][j])
                {
                    ret++;
                    bf(grid, i, j);
                }
            }
        }
        return ret;
    }
    void bf(vector<vector<char>>& grid, int i, int j)
    {
        queue<pair<int, int>> q;
        q.push({ i,j });
        vir[i][j] = true;
        while (q.size())
        {
            auto [a, b] = q.front();
            q.pop();
            for (int k = 0; k < 4; k++)
            {
                int x = a + dx[k], y = b + dy[k];
                if (x >= 0 && x < m && y >= 0 && y < n && grid[x][y] == '1' && !vir[x][y])
                {
                    q.push({ x,y });
                    vir[x][y] = true;
                }
            }
        }
    }
};
int main()
{
    return 0;
}